Description: This map from the U. S. Geological Survey Water Resources Investigation Report number 97-4011, Rainfall and Freshwater Discharge in the Indian River Basin, shows the average annual rainfall in the Indian River Basin from the period 1951 to 1980. The isolines show areas of equal mean annual rainfall in inches.Source: Lee Knowles, Jr. , USGS Water Resources Investigations Report 94-4193 (Tallahassee, FL: U. S. Geological Survey, 1995) 8Map Credit: Courtesy the University of South Florida Library